The prior art reveals a number of signalling devices that emit either a concentrated spot beam of light, for example a conventional flashlight or the like, or a diffuse light, for example a reading light or the like.
In environments containing smoke or of high turbidity, much of the light from sources having a wide beam is reflected back towards the source whereas a strong beam penetrates the turbidity while producing some ambient glow through reflection off the particles. This acts well as a beacon as well as providing better penetration of vision into the turbid medium than would otherwise be possible with a wide beam. On the other hand, in smoke free conditions or conditions of low turbidity, a concentrated beam is poorly visible from the sides.
What is needed for use in all such situations, therefore, is a light emitting device that simultaneously emits a wide angle beam visible from the sides and a concentrated beam.